Immunomedics Inc. is expected to present results of itslymphoma imaging and radioimmunotherapy programs todayat the American Association for Cancer Research conference.
"It's exciting," said Chairman David Goldenberg, "because forthe first time we're getting the opportunity to see treatmentresponses at radiation doses much lower than expected."
The Morris Plans, N.J., company (NASDAQ:IMMU) has threepresentations scheduled for the Orlando, Fla., meeting today.
In a Phase I/II trial, the company has attached radioactiveiodine to a monoclonal antibody that targets lymphoma,ImmuRAIT-LL2. In a second-generation approach, thecompany is testing rhenium-188 in a mouse model. Rheniumgenerates more beta emissions in a wider path than the iodineisotope, Goldenberg said, and has less gamma emissions, whichare less effective in killing cells. Rhenium poses the potential ofadministering a more discrete radiation dose, capable ofdestroying tumors about six times as large, he said.
The isotope can be milked from a tungsten source on site,although generators would have to be created commerciallyafter the technology is advanced, he said. Rhenium generatorsare now only available for experimental use.
Immunomedics also uses the more commonly availabletechnetium-99m on an antibody fragment to image lymphoma.Its ImmuRAID-LL2 is in Phase II studies in non-Hodgkin's B-cell lymphoma, in which it correctly identified at least oneknown lesion in each of 10 patients. The agent also identifiedundiagnosed lesions.
The compound could help identify the extent of malignantdisease, Goldenberg said, and might show whether tumors arestill viable since the antibody wouldn't be expected to bind todead cells that have stopped producing antigens. Residualtumors as small as half a centimeter might also be visualized,he said.
The antibody fragment used in imaging is targeted for"humanization," said David Ortlieb, company president, so itcould be a basis of therapeutic agents that could beadministered repeatedly without provoking an allergicresponse.
-- Nancy Garcia Associate Editor
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